The present invention relates to a method and apparatus for making a dry sheet-like sample of solid particles from a suspension. It also relates to a method and apparatus for measuring the pulp concentration of a dilute fiber suspension or pulp liquor.
In the paper making industry, control of the pulp concentration is a very important matter to a stable paper-making operation and a uniform quality of paper pulp obtained.
The pulp concentration is a proportion of the oven-dry weight of fiber contents in dilute fiber suspension to the total weight of the dilute fiber suspension which is indicated in terms of weight percent.
According to a conventional practice, the measurement of the pulp concentration is achieved by first manually sampling a part of the dilute fiber suspension into a measuring cup as it flows through a pipe. Then, the total weight of the sampled dilute fiber suspension is measured.
Subsequently, the sampled pulp liquor is squeezed to extract fiber contents which are in turn extended into a wet sheet-like intermediate fiber mat or sample. The intermediate sample is dried by heating within an oven under appropriate heating conditions such, for example, as at 130.degree. C. for 2 hours. Thus, a dry sheet-like final sample or fiber mat is obtained.
The dry final sample is weighed for its oven-dry weight (also known as "absolute dry weight") and a proportion of the oven-dry weight of the dry final sample to the total weight of the dilute fiber suspension is calculated. The pulp concentration is thus obtained.
The conventional measurement of the pulp concentration substantially entirely depends on the manual operation and hence is a time-consuming practice. Due to the manual operation, the measuring accuracy is relatively low.